Technical Field
Embodiments of the invention relate generally to vehicles powered from replaceable energy storage devices. Particular embodiments relate to battery-powered electric vehicles.
Discussion of Art
Generally, vehicles that are not continuously powered from an external source incorporate some kind of energy storage apparatus, e.g., a battery or fuel tank, which requires periodic recharging or refilling. In the context of work vehicles (e.g., a mine vehicle, a rail locomotive, or other off-highway vehicle/OHV), however, it is generally desirable to reduce or substantially eliminate the downtime required for recharging or refilling a battery or fuel tank. For example, it may be desirable for a battery powered electric vehicle to have provided a battery exchange apparatus for quickly removing an expended battery and replacing it with a fully charged battery. For such an apparatus it may be necessary for the vehicle to be positioned at a particular exchange position to enable removal and replacement of batteries, etc.
In certain work environments, however, there may be restrictions on where batteries can be exchanged. For example, underground gallery mining operations can extend as deep as two miles vertically and for many miles horizontally into the ground. Although elevators in vertical shafts may be used for lifting ore up from the sub-levels of a mine, it is prohibitively expensive to put vertical shafts all along a miles-long gallery. Accordingly, vehicles are used to haul the ore along the galleries to the extraction shafts. As ventilation of underground mines already is a challenging task, it is desirable for such vehicles to have minimal emissions. Presently, some ore haulers are built with engines certified to “Tier 3” emissions standards. It would be more desirable to build these hauler vehicles as zero-emissions vehicles, e.g., powered by stored energy, so as to avoid any additional ventilation loading from their operation. Recharging the batteries of such vehicles, however, is potentially problematic. For cost reasons, battery-charging stations can be provided only in selected areas of a mining operation, typically close to an extraction shaft.
Electric powered vehicles are currently used for crew transport within mines. Because crew transport is a relatively low-repetition event (typically, one inbound trip and one outbound trip per shift), a battery powered crew transport vehicle often is able to sit at a charging station throughout a shift. This relatively high availability for charging enables use of charging stations with relatively low power draw and thereby reduces the equipment and operational costs of recharging battery powered crew transport vehicles.
In contrast to crew transport vehicles, mine operations typically have ore hauler vehicles in near-continuous motion, pausing only to load and unload. Loading locations are continuously moving as the work face advances or retreats, and it is not feasible to keep relocating battery-charging stations at loading locations. Although unloading locations are fixed (adjacent the conveyors that travel up the extraction shafts) during unloading, an ore hauler vehicle is subject to large and somewhat unpredictable mechanical loads. Additionally, each ore hauler vehicle is scheduled to clear loading and unloading locations as rapidly as possible so that a next ore hauler can begin to load or dump. As will be appreciated, the high capacity batteries essential to powering an ore hauler, which must transport loads far heavier than a few crew members, would take too long to recharge at these locations even at relatively high electrical power (e.g., on the order of thousands of watts).
For at least these reasons, loading and unloading locations are not optimal locations for recharging an ore hauler vehicle battery. Accordingly, use of battery powered ore hauler vehicles would likely require scheduling an additional stop or sidetrack along the haul route to permit for battery recharge in a location away from loading, hauling, and unloading operations. Sidetracking an ore hauler, however, results in excessive time in which the hauler is not loading, hauling, and unloading. This excessive off-task time has been an obstacle to adoption of battery powered hauler vehicles, which otherwise would be desirable at least because they would reduce the ventilation loading in deep galleries. Another hurdle to adoption has been the cost of energy storage devices capable to support hours of operation along with rapid full charging.
Therefore, it may be desirable to provide systems and methods for recharging vehicle-mounted energy storage devices that differ from currently available systems and methods, for example, to enable opportunity (partial) charging of vehicle-mounted energy storage devices and/or to enable battery exchange without having to bring a vehicle to a particular battery exchange location.